Hydroxychloroquine serum concentration in coronavirus disease 2019 (COVID-19) patients: a retrospective study

Algeria has adopted a therapeutic protocol using hydroxychloroquine (HCQ) as a first-line treatment for patients with coronavirus disease 2019 (COVID-19). The administration of HCQ must be accompanied by appropriate cardiac and therapeutic pharmacological monitoring to avoid side effects and toxicity. This work is a retrospective descriptive study aiming to estimate the HCQ levels of COVID-19 patients. HCQ concentrations in blood samples from COVID-19 patients were determined using high performance liquid chromatography with diode array dtector (HPLC-DAD) after liquid-liquid extraction of plasma. The coefficient of determination (r(2)) of this method was 0.9999. The limits of quantification and detection were 0.05 mg/L and 0.02 mg/L, respectively, with coefficients of variance less than 6%. Patient monitoring was performed following recommendations for the therapeutic pharmacological monitoring of HCQ in patients treated for SARS-CoV-2 (COVID-19) infection validated by the coordinated action (AC43) of the National Agency for Research on AIDS and Viral Hepatitis (ANRS) and Therapeutic Pharmacological Monitoring and Personalization of Treatments (STP-PT) group. A total of 267 blood samples from 240 patients were analyzed, 49% for males and 51% for females. More than a third of the patients were 60-80years old. The majority (68%) of the HCQ concentrations were between 0.1 and 1 mg/L. Additionally, more than 20% were between 0.05 and 0.1 mg/L, while only 7.5% were less than 0.05mg/L and 1.5% were greater than 1 mg/L. In summary, patients with COVID-19 show a good tolerance to HCQ in the majority of cases.